This invention relates to sensor devices and provides a technique applicable to, for example, a sensor device with an inductor.
Wattmeters for measuring the electric power passing through a power line use inductors. A change in the amount of current flowing through the power line makes a change in the strength of the magnetic field generated from the power line. Electric power is generated in the inductors in accordance with the change in the magnetic field strength. The wattmeters monitor the electric power to detect the amount of electric power flowing in the power line.
Generally, a wattmeter is provided with a magnetic core. The magnetic core is shaped as if it encloses the power line. However, Japanese Unexamined Patent Publication No. 2011-185914 discloses a coreless-type current sensor using a multilayer printed circuit board. In this publication, the multilayer printed circuit board is provided with a coil. This coil is formed with two different interconnect layers of the multilayer printed circuit board and vias coupling these interconnect layers. A hall IC is embedded inside the coil. The current to be detected flows through the coil.